You're right, there are no good and free JS libraries for gantt charts (or even timelines). It is a non-trivial problem domain. I know, because I helped buil

You're right, there are no good and free JS libraries for gantt charts (or even timelines). It is a non-trivial problem domain. I know, because I helped build a product (https://peachyplan.com https://peachyplan.com) much like Notion's timeline view :) The notion team did a phenomenal job. This is one of the best timeline views I've seen, and I've looked at hundreds.